| 摘要 |
PROBLEM TO BE SOLVED: To avoid influence of a reflecting wave component of a receiving electric wave from an onboard transmitter and improve precision of position measuring of a vehicle. SOLUTION: Antenna arrays A, B have two antenna elements respectively. Two receiving electric waves by elements 501A, 502A extract phase-related data (the sine wave function and the cosine wave function of a phase differenceΔϕA) with a phase comparator 405, the amplitude thereof (A1, A2) is found with AM wave detectors 431, 432, and taken in a computer. If an amplitude ratio A1/A2 is in an allowable range, CPU 421 calculates the phase differenceΔϕA from the sine wave function and the cosine wave function, and the antenna 501A and the azimuthθ1 of a transmitting source are calculated fromΔϕA. The receiving electric waves of 501B and 502B is similarly processed, if another amplitude ratio B1/B2 is in the allowable range, the antenna 501B and the azimuthθ2 of another transmitting source are calculated. The transmitting source fromθ1 andθ2, namely, the position of a vehicle is found. However, when the amplitude ratio is out of the allowable range, measuring data is canceled.
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